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Connectivity Components - App Inventor for Android

Table of Contents

ActivityStarter

A component that can launch an activity using the StartActivity method.

Activities that can be launched include:

Starting another App Inventor for Android app.
To do so, first find out the class of the other application by downloading the source code and using a file explorer or unzip utility to find a file named "youngandroidproject/project.properties".
The first line of the file will start with "main=" and be followed by the class name; for example, main=com.gmail.Bitdiddle.Ben.HelloPurr.Screen1. (The first components indicate that it was created by Ben.Bitdiddle@gmail.com.)
To make your ActivityStarter launch this application, set the following properties:

ActivityPackage to the class name, dropping the last component (for example, com.gmail.Bitdiddle.Ben.HelloPurr)

ActivityClass to the entire class name (for example, com.gmail.Bitdiddle.Ben.HelloPurr.Screen1)

Starting the camera application by setting the following properties:

Action: android.intent.action.MAIN

ActivityPackage: com.android.camera

ActivityClass: com.android.camera.Camera

Performing web search. Assuming the term you want to search for is "vampire" (feel free to substitute your own choice),
set the properties to:

Opening a browser to a specified web page. Assuming the page you want to go to is "www.facebook.com" (feel free to substitute your own choice), set the properties to:

Action: android.intent.action.VIEW

DataUri: http://www.facebook.com

Properties

Action

ActivityClass

ActivityPackage

DataType

DataUri

Extras

Accepts a list of pairs which are used as key/value pairs in
the “Extra” field of the activity

ExtraKey(Obsolete)

ExtraValue(Obsolete)

Result

ResultName

ResultType

ResultUri

Events

AfterActivity(text result)

Event raised after this ActivityStarter returns.

ActivityCanceled()

Event raised if this ActivityStarter returns because the activity was canceled.

Methods

text ResolveActivity()

Returns the name of the activity that corresponds to this ActivityStarter, or an empty string if no corresponding activity can be found.

StartActivity()

Start the activity corresponding to this ActivityStarter.

BluetoothClient

Bluetooth client component

Properties

AddressesAndNames

The addresses and names of paired Bluetooth devices

Available

Whether Bluetooth is available on the device

CharacterEncoding

DelimiterByte

Enabled

Whether Bluetooth is enabled

HighByteFirst

IsConnected

Secure

Whether to invoke SSP (Simple Secure Pairing), which is supported on devices with Bluetooth v2.1 or higher. When working with embedded Bluetooth devices, this property may need to be set to False. For Android 2.0-2.2, this property setting will be ignored.

Events

none

Methods

number BytesAvailableToReceive()

Returns an estimate of the number of bytes that can be received without blocking

boolean Connect(text address)

Connect to the Bluetooth device with the specified address and the Serial Port Profile (SPP). Returns true if the connection was successful.

boolean ConnectWithUUID(text address, text uuid)

Connect to the Bluetooth device with the specified address and UUID. Returns true if the connection was successful.

Disconnect()

Disconnect from the connected Bluetooth device.

boolean IsDevicePaired(text address)

Checks whether the Bluetooth device with the specified address is paired.

number ReceiveSigned1ByteNumber()

Receive a signed 1-byte number from the connected Bluetooth device.

number ReceiveSigned2ByteNumber()

Receive a signed 2-byte number from the connected Bluetooth device.

number ReceiveSigned4ByteNumber()

Receive a signed 4-byte number from the connected Bluetooth device.

list ReceiveSignedBytes(number numberOfBytes)

Receive multiple signed byte values from the connected Bluetooth device. If numberOfBytes is less than 0, read until a delimiter byte value is received.

text ReceiveText(number numberOfBytes)

Receive text from the connected Bluetooth device. If numberOfBytes is less than 0, read until a delimiter byte value is received.

number ReceiveUnsigned1ByteNumber()

Receive an unsigned 1-byte number from the connected Bluetooth device.

number ReceiveUnsigned2ByteNumber()

Receive a unsigned 2-byte number from the connected Bluetooth device.

number ReceiveUnsigned4ByteNumber()

Receive a unsigned 4-byte number from the connected Bluetooth device.

list ReceiveUnsignedBytes(number numberOfBytes)

Receive multiple unsigned byte values from the connected Bluetooth device. If numberOfBytes is less than 0, read until a delimiter byte value is received.

Send1ByteNumber(text number)

Send a 1-byte number to the connected Bluetooth device.

Send2ByteNumber(text number)

Send a 2-byte number to the connected Bluetooth device.

Send4ByteNumber(text number)

Send a 4-byte number to the connected Bluetooth device.

SendBytes(list list)

Send a list of byte values to the connected Bluetooth device.

SendText(text text)

Send text to the connected Bluetooth device.

BluetoothServer

Bluetooth server component

Properties

Available: boolean

Tell whether Bluetooth is available on the Android device.

CharacterEncoding: text

The character encoding to use when sending and receiving text.

DelimiterByte: number

The delimiter byte to use when passing a negative number for the
numberOfBytes parameter when calling ReceiveText, ReceiveSignedBytes,
or ReceiveUnsignedBytes.

Enabled: boolean

Tell whether Bluetooth is enabled.

HighByteFirst: boolean

Whether 2 and 4 byte numbers should be sent and received with
the high (or most significant) byte first. Check the documentation for
the device with which your app will be communicating for the
appropriate setting. This is also known as big-endian.

IsAccepting: boolean

Tell whether this BluetoothServer component is accepting an
incoming connection.

IsConnected: boolean

Tell whether a Bluetooth connection has been made.

Events

ConnectionAccepted()

Indicates that a bluetooth connection has been accepted.

Methods

AcceptConnection(text serviceName)

Accept an incoming connection with the Serial Port Profile
(SPP).

AcceptConnectionWithUUID(text serviceName, text uuid)

Accept an incoming connection with a specific UUID.

number BytesAvailableToReceive()

Returns an estimate of the number of bytes that can be received
without blocking

Disconnect()

Disconnect from the connected Bluetooth device.

number ReceiveSigned1ByteNumber()

Receive a signed 1-byte number from the connected Bluetooth
device.

number ReceiveSigned2ByteNumber()

Receive a signed 2-byte number from the connected Bluetooth
device.

number ReceiveSigned4ByteNumber()

Receive a signed 4-byte number from the connected Bluetooth
device.

list ReceiveSignedBytes(number numberOfBytes)

Receive multiple signed byte values from the connected Bluetooth
device. If numberOfBytes is less than 0, read until a delimiter byte
value is received.

text ReceiveText(number numberOfBytes)

Receive text from the connected Bluetooth device. If
numberOfBytes is less than 0, read until a delimiter byte value is
received.

number ReceiveUnsigned1ByteNumber()

Receive an unsigned 1-byte number from the connected Bluetooth
device.

number ReceiveUnsigned2ByteNumber()

Receive a unsigned 2-byte number from the connected Bluetooth
device.

number ReceiveUnsigned4ByteNumber()

Receive a unsigned 4-byte number from the connected Bluetooth
device.

list ReceiveUnsignedBytes(number numberOfBytes)

Receive multiple unsigned byte values from the connected
Bluetooth device. If numberOfBytes is less than 0, read until a
delimiter byte value is received.

Web

Properties

AllowCookies

Whether the cookies from a response should be saved and used in subsequent requests. Cookies are only supported on Android version 2.3 or greater.

RequestHeaders

The request headers, as a list of two-element sublists. The first element of each sublist represents the request header field name. The second element of each sublist represents the request header field values, either a single value or a list containing multiple values.

ResponseFileName

The name of the file where the response should be saved. If SaveResponse is true and ResponseFileName is empty, then a new file name will be generated.

Methods

Converts a list of two-element sublists, representing name and value pairs, to a
string formatted as application/x-www-form-urlencoded media type, suitable to pass to
PostText.

ClearCookies()

Clears all cookies for this Web component.

Delete()

Performs an HTTP DELETE request using the Url property and retrieves the
response.
If the SaveResponse property is true, the response will be saved in a file
and the GotFile event will be triggered. The ResponseFileName property
can be used to specify the name of the file.
If the SaveResponse property is false, the GotText event will be
triggered.

Get()

Performs an HTTP GET request using the Url property and retrieves the
response.
If the SaveResponse property is true, the response will be saved in a file
and the GotFile event will be triggered. The ResponseFileName property
can be used to specify the name of the file.
If the SaveResponse property is false, the GotText event will be
triggered.

text HtmlTextDecode(text htmlText)

Decodes the given HTML text value. HTML character entities such as &amp;, &lt;, &gt;, &apos;, and &quot; are changed to &, <, >, ', and ". Entities such as &#xhhhh, and &#nnnn are changed to the appropriate characters.

any JsonTextDecode(text jsonText)

Decodes the given JSON encoded value to produce a corresponding AppInventor value.
A JSON list [x, y, z] decodes to a list (x y z), A JSON object with name A and value B,
(denoted as A:B enclosed in curly braces) decodes to a list
((A B)), that is, a list containing the two-element list (A B).

PostFile(text path)

Performs an HTTP POST request using the Url property and data from the specified file.If the SaveResponse property is true, the response will be saved in a file and the GotFile event will be triggered. The ResponseFileName property can be used to specify the name of the file.If the SaveResponse property is false, the GotText event will be triggered.

PostText(text text)

Performs an HTTP POST request using the Url property and the specified text.The characters of the text are encoded using UTF-8 encoding.If the SaveResponse property is true, the response will be saved in a file and the GotFile event will be triggered. The responseFileName property can be used to specify the name of the file.If the SaveResponse property is false, the GotText event will be triggered.

PostTextWithEncoding(text text, text encoding)

Performs an HTTP POST request using the Url property and the specified text.The characters of the text are encoded using the given encoding.If the SaveResponse property is true, the response will be saved in a file and the GotFile event will be triggered. The ResponseFileName property can be used to specify the name of the file.If the SaveResponse property is false, the GotText event will be triggered.

PutFile(text path)

Performs an HTTP PUT request using the Url property and data from the specified file.If the SaveResponse property is true, the response will be saved in a file and the GotFile event will be triggered. The ResponseFileName property can be used to specify the name of the file.If the SaveResponse property is false, the GotText event will be triggered.

PutText(text text)

Performs an HTTP PUT request using the Url property and the specified text.The characters of the text are encoded using UTF-8 encoding.If the SaveResponse property is true, the response will be saved in a file and the GotFile event will be triggered. The responseFileName property can be used to specify the name of the file.If the SaveResponse property is false, the GotText event will be triggered.

PutTextWithEncoding(text text, text encoding)

Performs an HTTP PUT request using the Url property and the specified text.The characters of the text are encoded using the given encoding.If the SaveResponse property is true, the response will be saved in a file and the GotFile event will be triggered. The ResponseFileName property can be used to specify the name of the file.If the SaveResponse property is false, the GotText event will be triggered.

text UriEncode(text text)

Encodes the given text value so that it can be used in a URL.

any XMLTextDecode(text XmlText)

Decodes the given XML string to produce a list structure. See the App Inventor documentation on "Other topics, notes, and details" for information.